The major difference between the Bingham model and Newtonian fluids is?

• A. Bingham model has a yield point
• B. Newtonian fluids have a yield point
• C. Both have a yield point
• D. Neither has a yield point

Answer: (D)

Yield stress is the key idea here. Bingham plastics behave as a solid until the applied shear stress reaches a finite value, called the yield stress. Once that threshold is surpassed, they flow with a linear relation that adds the yield stress to the viscous term: tau = tau_y + mu_p * gamma_dot. Newtonian fluids, on the other hand, have no yield stress and begin to flow immediately under any applied shear, with tau = mu * gamma_dot. So the major difference is the presence of a yield point in the Bingham model versus none in Newtonian fluids. The statement that neither has a yield point doesn’t fit the defining behavior of Bingham fluids.